1. Field of the Invention. This invention pertains to alert systems, and more particularly to signaling devices useful in ice fishing.
2. Description of the Prior Art. Various types of equipment have been developed for fishing through the ice. For example, tipups are well known and widely used.
Although ice fishing tipups are constructed with different designs and operating features, they invariably include components that hold a fishing line and a means that signals a fisherman of a strike on the line. The signaling means can be audio or visual or a combination of the two. U.S. Pat. Nos. 2,170,000; 3,359,673; and 4,246,716 show tipups that include both electrically operated light and sound emitting devices. The fish detecting systems of U.S. Pat. Nos. 4,437,255; 4,928,419; and 5,097,618 employ transmitters that activate radio receivers worn by a fisherman. The tipups of U.S. Pat. Nos. 2,170,000; 4,928,419; and 5,097,618 also include flags that snap from a horizontal attitude to a vertical attitude in response to a fish strike.
Despite the variety of tipup signaling devices available, they nevertheless are not completely satisfactory. Some switches for prior electrically operated signaling devices utilize mercury. Examples of mercury tipup switches may be seen in U.S. Pat. Nos. 3,882,629; 3,918,191; 4,479,321; 4,766,688; and 5,488,796. For environmental reasons, mercury switches are highly undesirable.
Many prior signaling devices possess the further handicap of being built into the tipup itself, so that failure of the signaling device limits the usefulness of the tipup. In addition, built-in signaling devices tend to deteriorate when the tipups are stored during the summer months. Many of the prior signaling devices are also undesirably complicated and expensive.
Accordingly, there is room for improvement in ice fishing tipups.